The present invention is based on the phenomenon of dielectrophoresis--the translational motion of neutral matter caused by polarization effects in a non-uniform electric field. The dielectrophoresis phenomenon was first recorded over 2500 years ago when it was discovered that rubbed amber attracts bits of fluff and other matter. Over 300 years ago, it was observed that water droplets change shape as they approach a charged piece of amber. The basic concept of dielectrophoresis is examined in detail in a text entitled Dielectrophoresis by Herbert H. Pohl, published in 1978 by the Cambridge University Press. Further discussion of this phenomenon also can be found in an article by W. F. Pickard entitled "Electrical Force Effects in Dielectric Liquids", Progress in Dielectrics 6 (1965)--J. B. Birks and J. Hart, Editors.
All known practical applications of the dielectrophoresis phenomenon have been directed to either particle separators or clutches. For example, U.S. Pat. No. 1,533,711 discloses a dielectrophoretic device that removes water from oil; U.S. Pat. No. 2,086,666 discloses a dielectrophoretic device which removes wax from oil; U.S. Pat. No. 2,665,246 discloses a dielectrophoretic separator used in a sludge treatment process, U.S. Pat. No. 2,914,453 provides for separation of solid polymeric material from fluid solvents; U.S. Pat. No. 3,162,592 provides for separation of biological cells; U.S. Pat. No. 3,197,393 discloses a separator using centripetal acceleration and the dielectrophoretic phenomenon; U.S. Pat. No. 3,304,251 discloses dielectrophoretic separation of wax from oil; U.S. Pat. No. 3,431,441 provides a dielectrophoretic separator which removes polarizable molecules from plasma; U.S. Pat. No. 3,980,541 discloses separation of water from fluid; and U.S. Pat. No. 4,164,460 provides for removal of particles from a liquid. U.S. Pat. Nos. 3,687,834; 3,795,605; 3,966,575; and 4,057,482 disclose other dielectrophoretic separators for removing particulates and water from a fluid. Other separators, not necessarily dielectrophoretic separators, are disclosed in U.S. Pat. Nos. 465,822; 895,729; 3,247,091 and 4,001,102.
U.S. Pat. No. 2,417,850 discloses a clutch mechanism using the dielectrophoretic phenomenon.
The object of the present invention is to provide a reaction chamber or housing in which one or more chemicals can be selectively manipulated to different locations within the chamber using the dielectrophoresis phenomenon. A variety of apparatus for performing chemical manipulations are known to the art. Such apparatus provide mechanical manipulation (such as by pressurized fluid transfer), inertial or gravimetric manipulation (such as by centrifigation), or phase separation (such as by distillation). Automated chemical analysis can be accomplished, for example, by automatic titrators, which substitute electrically operated components, such as solenoid driven stopcocks, for operations normally performed manually. Automated chemical synthesizers as, for example, protein sequencers are also known.
The present invention provides a technique for electronic manipulation of chemicals using the phenomenon of dielectrophoresis. Dielectrophoretic forces are used to selectively position, mix, separate and transport one or more chemical species within a housing. For example, chemical species may be transported to a typical reaction site, such as heated catalytic surfaces to induce a chemical reaction. Likewise, chemicals may be transported to analytical devices, such as absorption spectrometers. Dielectrophoretic manipulation of one or more chemicals is well suited for automatic control such as, for example, direct computer control.